Copolyether ester elastomers are commonly used for molded parts inside automobiles. It has been found that in many cases, some molded parts have the tendency to "bloom." This surface bloom is undesirable since it can affect the color and gloss of the finished parts. It can also make surface scratches much more visible. This bloom is believed to be a migration of some of the ingredients in the copolyether ester elastomer to the surface, and once there will form a light colored haze.
Analysis on the bloom shows the presence of different diamines, including those that promote the formation of polyurethane such as triethylenetriamine, DABCO (triethylene diamine), N,N-diethylcyclohexylamine, N,N-dimethyloctylamine; 1,5-diazabicyclo[4.3.0]non-5-ene (DBN); N,N,N',N'tetramethyl hexamethylene diamine, and N,N,N',N'tetramethyl bis (2-aminoethyl) ether. Such diamines are usually found in components of the polyurethane foam commonly used in the interior of automobiles.
It is believed that these diamines evaporate out of the polyurethane foam present in the air inside automobiles. It is also believed that in the presence of these diamines, acid-terminated oligomers can migrate to the surface of the copolyether ester elastomers, forming insoluble salts.
A need exists for copolyether ester elastomer compositions which are bloom-resistant when exposed to air containing amines, preferably, without an increase in melt viscosity.